POPULATION SUBDIVISION AND ADAPTATION IN ASEXUAL POPULATIONS OF SACCHAROMYCES CEREVISIAE
POPULATION SUBDIVISION AND ADAPTATION IN ASEXUAL POPULATIONS OF SACCHAROMYCES CEREVISIAE
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DOI：
10.1111/j.1558-5646.2011.01569.x
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发表时间：
2012-06-01
期刊：
影响因子：
3.3
通讯作者：
Desai, Michael M.
中科院分区：
文献类型：
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作者：
Kryazhimskiy, Sergey;Rice, Daniel P.;Desai, Michael M.
种群细分限制了个体之间的竞争，这会对适应产生深远的影响。与充分混合的群体相比，细分的群体在任何给定时间都保持更多的遗传多样性，从而探索更大的基因型空间。与此同时，有益的突变需要更长的时间才能在这些群体中传播，因此细分群体不能像充分混合的群体那样有效地利用已发现的突变。在给定环境中，细分是否抑制或促进适应取决于探索与利用的相对重要性，而这又取决于有益突变之间的上位结构。在这里，我们通过进化 976 个具有多个地理细分程度的独立无性芽殖酵母群体，研究了探索与利用对于适应的相对重要性。我们发现，细分系统地抑制了适应：即使是细分群体中最幸运的群体，平均而言也无法发现比充分混合群体所发现的基因型更适合的基因型。因此，利用已发现的突变对于我们系统的适应比彻底探索突变邻域更为重要，而增加细分会减慢适应速度。
Population subdivision limits competition between individuals, which can have a profound effect on adaptation. Subdivided populations maintain more genetic diversity at any given time compared to well-mixed populations, and thus explore larger parts of the genotype space. At the same time, beneficial mutations take longer to spread in such populations, and thus subdivided populations do not exploit discovered mutations as efficiently as well-mixed populations. Whether subdivision inhibits or promotes adaptation in a given environment depends on the relative importance of exploration versus exploitation, which in turn depends on the structure of epistasis among beneficial mutations. Here we investigate the relative importance of exploration versus exploitation for adaptation by evolving 976 independent asexual populations of budding yeast with several degrees of geographic subdivision. We find that subdivision systematically inhibits adaptation: even the luckiest demes in subdivided populations on average fail to discover genotypes that are fitter than those discovered by well-mixed populations. Thus, exploitation of discovered mutations is more important for adaptation in our system than a thorough exploration of the mutational neighborhood, and increasing subdivision slows adaptation.